(A61K31/44,A61K 45/06,A61K 9/20,A61K 9/48)
The invention belongs to the field of pharmaceutical industry and relates to a novel medicinal formulation with controlled release of active substances on the basis of anhydrous (i.e. non-aqueous) granulation of the active substances and dried pharmaceutically acceptable auxiliary substances. By the invention a technologically simple manufacture of a stable pharmaceutical formulation with controlled release of active substances is made possible.
More specifically, the invention relates to a novel pharmaceutical formulation with controlled release of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating. Further, the invention relates to a novel method of stabilization of such unstable active substances and to a process for the preparation of the novel pharmaceutical formulation of such unstable active substances.
There exists a constant need for developing pharmaceutical formulations wherein in a technologically simple way there would be achieved a good stability of active substances that are unstable in acidic medium unstable when stored for longer periods of time in the presence of water and at the same time sensitive to hearing. For the manufacture of hitherto known pharmaceutical formulations containing such active substances, technological processes have been used, wherein also water, wherein such active substances are not stable, has been used as a solvent and therefore the required stability has been achieved especially by the addition of basic substances to the active substance or by using the active substance in the form of a salt thereof. Namely, basic substances create a basic pH in the environment of the active substance, whereat such active substances are more stable.
The first literature data upon stabilization of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, relate to the transformation of such active substances to salts thereof, e.g. the transformation of omeprazol, which is a substance unstable in acidic medium, to different salts of omeprazol is disclosed in EP-A-124495. A pharmaceutical formulation with a magnesium salt of omeprazol is disclosed in WO 95/01783 and in WO 96/01622.
The use of basic inorganic salts of magnesium and/or calcium for stabilization of benzimidazoles is disclosed in EP-A-237200. A stable pharmaceutical formulation is prepared by a homogenous blending of the active substance with basic inorganic salts of magnesium and/or calcium and pharmaceutically acceptable auxiliary substances. The obtained granules, pellets or tablets are then coated with a gastro-resistant (i.e. enteric) coating.
The stabilization of omeprazol as disclosed in EP-A-247983 is achieved by means of a pharmaceutical formulation, wherein the active substance or a salt thereof is blended with different alkaline substances in the core and thereon one or more intermediate coatings (i.e. separating layers) are applied, followed by a gastro-resistant coating. In EP-A496437, which is a divisional of above EP-A-247983, a pharmaceutical composition comprising a benzimidazole active compound, a binder, a cellulose derivative, and a surfactant is disclosed. The stabilization of active substances that are unstable in acidic medium by adding different alkaline compounds is disclosed in several patent applications, e.g. in WO 94/02140 the addition of a coprecipitate Al(QH)3-NaHCO3 is disclosed, in U.S. Pat. No.5,232,706 the addition of different alkaline compounds is disclosed and in EP-A-519365 there is disclosed a pharmaceutical formulation with pantoprazol, which is a substance unstable in acidic medium, and with alkaline compounds in the core. Additionally, the stability at prolonged storage is enhanced with the addition of TiO2 to the core with omeprazol (WO 96/37195).
The formation of a complex of active substances unstable in an acidic medium, with cyclodextrins in an alkaline solution is disclosed in U.S. Pat. No. 5,399,700. The stabilization is achieved by incorporating a particular molecule of the active substance into a cyclodextrin molecule. Similarly, in WO 96/38175 the incorporating of molecules of benzimidazole derivatives into branched derivatives of cyclodextrin-carboxylic acid is disclosed.
In WO 93/25204 there is disclosed a stable pharmaceutical formulation of omeprazol microgranules containing a neutral core of sugar and starch, onto which core a layer of omeprazol and mannitol in equal quantities is applied. Similar pharmaceutical formulation for benzimidazole derivatives is also disclosed in WO 96/23500 and WO 97/12581. In a pharmaceutical formulation, disclosed in WO 97/12581, in an aqueous suspension a layer of omeprazol and hydroxypropylmethylcellulose is applied to inert cores of lactose. Other technologies of spraying an active substance onto inert cores are known as well (U.S. Pat. No. 5,246,714, EP-A-519144).
WO 96/24375 discloses a fixed formulation comprising an acid susceptible proton pump inhibitor and one or more antibacterial compounds. WO 83/03756 discloses the usage of anhydrous granulation to achieve rapid action of clometacine and to increase the biodisponibility of clometacine. EP-A-391374 relates to methods for the preparation of formulation of bromocriptine, which is very sensitive to moisture, light and temperature, by the incorporation of bromocriptine in an inert excipient.
The basic object of the invention is an improved stability of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating. This object is achieved by anhydrous granulation of the active substances and of dried pharmaceutically acceptable auxiliary substances for the preparation of pellet cores or granules. Pellet cores or granules thus prepared may under addition of dried pharmaceutically acceptable auxiliary substances be compressed into tablets, which are in the further procedure coated with a gastro-resistant coating. Between the tablet and the gastro-resistant coating one or more intermediate coatings may be optionally applied. Alternatively, the pellet cores or granules prepared by anhydrous granulation may be coated with a gastro-resistant coating and then filled into capsules, bags or compressed into tablets under the addition of dried pharmaceutically acceptable auxiliary substances. Between the pellet core or granules and a gastro-resistant coating one or more intermediate coatings may be optionally applied.
The object of the invention is a method for stabilizing active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, by means of anhydrous granulation of active substances and dried pharmaceutically acceptable auxliay substances for the preparation of pellet cores or granules.
In active substances that are unstable in the presence of water, stability at prolonged storage is a special problem. Hitherto known technological processes for the preparation of pharmaceutical formulations with controlled release of active substances are based upon the use of water or a mixture of water and organic solvents for the granulation of active substances and pharmaceutically acceptable auxiliary substances. During the process of drying the pellet cores or granules, water and other solvents are removed by heating. However, a complete removal of water from a pharmaceutical formulation is not possible according to hitherto known and disclosed processes. In active substances that are unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, a prolonged heating when drying should be avoided, which makes the removal of water even more difficult. Thus it was the basic object of the invention to prepare such a pharmaceutical formulation that will contain less than 1% water, preferably less than 0.5% water, and to use such a technological process which will use anhydrous medium in all steps of the process for the preparation of the pharmaceutical formulation, which applies to the process of granulation of active substances and pharmaceutically acceptable auxiliary substances as well as to the process of tie optional application of an intermediate coating and to the process of the application of a gastroresistant coating. At the same time, all pharmaceutically acceptable auxiliary substances used are dried before use, so that their weight loss at drying (i.e. water content) is less than 1.0% of the total weight of the pharmaceutical auxiliary substance, preferably less than 0.5%.
The unstability of active substances in an acidic medium is especially problematic after a peroral application of active substances, which decompose in an acidic gastric medium even before the systemic absorption. Thus the pharmaceutical formulation with such active substance should be prepared in such a way that it inhibits the dissolving of the active substance in the acidic gastric medium, but allows the dissolving of the active substance in the small intestine. This is achieved in such a way that onto the core with the active substance a gastro-resistant coating is applied, which protects the active substance against the acidic gastric medium, but is dissolved in the small intestine and thus a dissolution and systemic absorption of the active substance from the small intestine is made possible. Due to the acidity of the pharmaceutically acceptable auxiliary substances forming the gastro-resistant coating, a direct application of such compounds onto the pellet core with the active substance is problematic for two reasons. Because of a direct contact between the active substance that is unstable in an acidic medium and the acidic pharmaceutically acceptable auxiliary substance in the gastro-resistant coating, this gastro-resistant coating may cause the decomposition of the active substance during the storage of the pharmaceutical formulation. Secondly, after the peroral application of a pharmaceutical formulation with such active substance, a diffusion of water into the pellet core may occur in the stomach, the active substance in the core being stabilized with an alkaline substance. Due to the alkaline medium thus formed in the pellet core, the gastro-resistant coating is dissolved already in the acidic gastric medium and the active substance is caused to decompose. Therefore hitherto known pharmaceutical formulations with controlled release of active substances that are unstable in an acidic medium have one or more intermediate coatings incorporated between the pellet core and the gastro-resistant coating, which coatings enhance the stability of the active substance during storage and after peroral application. Since the stabilization method of the novel pharmaceutical formulation according to the invention is not based upon stabilizing the active substance with alkaline substances, but upon stabilization via an anhydrous granulation of the active substances and dried pharmaceutically acceptable auxiliary substances, it is not necessary to use an intermediate coating between the pellet core and the gastro-resistant coating to provide the required stability of the active substance.
It has been surprisingly found that anhydrous granulation of active substances and dried pharmaceutically acceptable auxiliary substances in the preparation of pellet cores or granules substantially enhances the stability of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, over Prior Art processes wherein water is used as a solvent. Organic solvents used in the process for the preparation of the novel pharmaceutical formulation with controlled release of active substances have lower boiling points than water and may be thus much easier removed from the pellet cores or granules. Because of the use of anhydrous granulation in the preparation of the novel pharmaceutical formulation according to the invention and due to an effective removal of solvents from the pharmaceutical formulation, no such medium is present which could transfer H30+ions between the pellet core with the active substance and the gastro-resistant coating. This is another reason that no intermediate coating to provide the required stability at prolonged storage is necessary. Since the present invention does not employ the manner of stabilizing active substances by adding alkaline substances, there is also no risk of the dissolution of the gastro-resistant coating after peroral application as described above.
Because of the use of a process of anhydrous granulation of active substances and dried pharmaceutically acceptable auxiliary substances in the preparation of pellet cores, granules or tablets, the cores thus prepared are porous. Therefore between the core and the gastro-resistant coating one or more intermediate coatings may be optionally applied in order to cover the irregularities on the core surface and to reduce the necessary amount of the gastro-resistant coating.
Further, the invention relates to a novel pharmaceutical formulation with controlled release of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, and of a combination of such active substances with other active substances.
A novel pharmaceutical formulation with controlled release of active substances according to the invention consists of a core and a gastro-resistant coating and between the core and the gastro-resistant coating one or more intermediate coatings may be optionally applied. Pellet cores or granules or tablets represent the core of the novel pharmaceutical formulation according to the invention.
The core of the novel pharmaceutical formulation with controlled release of active substances according to the invention contains active substances, a binder soluble in organic solvents, a cellulose ether, a surfactant and other common pharmaceutically acceptable auxiliary substances used in the preparation of solid pharmaceutical formulations such as fillers, disintegrators, swelling agents, glidants. Pharmaceutically acceptable auxiliary substances used are dried before use, so that their weight loss after drying is less than 1.0%, preferably less than 0.5 % of the total weight of the individual pharmaceutical auxiliary substance.
The novel pharmaceutical formulation with controlled release of active substances according to the invention may contain different active substances in an amount in the range from 0.1 to 95.0 wt.%, preferably from 0.5 to 80.0 wt.% with regard to the total weight of the core of the novel pharmaceutical formulation according to the invention. As active substances in the novel pharmaceutical formulation with controlled release of the active substance there may be used different active substances acting as analgesics, anticonvulsants, antiparkinsonics, anaestetics, antibiotics, antimalarial agents, antihypertensives, antihistaminics, antipyretics, alpha-blockers, alpha-adrenergic agonists, bactericides, bronchial dilators, beta-adrenergic stimulants, beta-adrenergic blockers, enzymes, contraceptives, cardiovascular active substances, calcium channel inhibitors, proton pump inhibitors, diuretics, hypnotics, hormones, hyperglycemics, hypoglycemics, muscle relaxants and contractors, parasympatho-mimetics, sedatives, sympathomimetics, tranquillizers, antimigraine agents, vitamins and any combinations thereof.
The novel pharmaceutical formulation with controlled release of active substances is especially suitable for benzimidazole derivatives such as lansoprazol, timoprazol, omeprazol, pantoprazol, leminoprazol, pariprazol, E-3810, S-4216, which are well known proton pump inhibitors, for pharmaceutically acceptable salts thereof, their optically active isomers and optically active isomers of the salts thereof.
The binder soluble in organic solvents, which is incorporated into the core of the pharmaceutical formulation according to the invention, makes possible an anhydrous granulation of the active substances and dried pharmaceutically acceptable auxiliary substances and acts as a binder in the preparation of pellet cores or granules. The solubility of the binder in organic solvents is essential for the preparation of pellet cores or granules according to the process of anhydrous granulation of active substances and dried pharmaceutically acceptable auxiliary substances. As an example of a binder soluble in organic solvents, there can be used the polymer polyvinyl pyrrolidone with the K-value (the relative viscosity of a compound in an aqueous solution with respect to water) in the range from 10 to 95, preferably in the range from 24 to 32, having an average molecular weight in the range from 2000 g/mole to 1100000 g/mole, preferably in the range from 25000 g/mole to 50000 g/mole. The binder soluble in organic solvents is present in the core of the novel pharmaceutical formulation according to the invention in an amount from 1 to 30 wt.%, preferably from 2 to 15 wt.% with regard to the total core weight. The used binder soluble in organic solvents is dried before use so that its weight loss at drying is less than 1.0%, preferably less than 0.5%.
The cellulose ether in the core of the novel pharmaceutical formulation according to the invention acts as a binder and at the same time as a disintegrator. As the cellulose ether there can be used methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, propyl cellulose, hydroxypropyl cellulose, lower-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, preferably lower-substituted hydroxypropyl cellulose having the content of hydroxypropoxy groups in the range of from 5 to 16%. The cellulose ether is present in the core of the novel pharmaceutical formulation according to the invention in an amount from 2 to 60 wt.%, preferably from 5 to 30 wt.% with regard to the total core weight. The cellulose ether used is dried before use so that its weight loss at drying is less than 1.0%, preferably less than 0.5%.
The surfactant added into the core improves the wettability of the dried pharmaceutically acceptable auxiliary substances in the preparation of the novel pharmaceutical formulation according to the invention. The surfactant also improves the wettability, solubility and dissolution rate of the active substances after peroral application of the novel pharmaceutical formulation according to the invention. As the surfactant there may be used ionic surfactants such as sodium lauryl sulfate, or non-ionic surfactants such as different types of poloxamers (copolymers of polyoxyethylene and polyoxypropylene), natural or synthetic lecitins as well as esters of sorbitan and fatty acids (such as Span(copyright) (Atlas Chemie)), esters of polyoxyethylenesorbitan and fatty acids (such as Polisorbates or Tween(copyright) (Atlas Chemie)), polyoxyethylated hydrogenated castor oils (such as Cremophor(copyright) (BASF)), polyoxyethylene stearates (such as Myrj(copyright) (Atlas Chemie)) or any combinations of the said surfactants. The surfactant is present in the core in an amount from 0.1 to 20.0 wt.%, preferably from 0.2 to 10.0 wt.% with regard to the total core weight. The surfactant used is dried before use so that its weight loss after drying is less than 1.0%, preferably less than 0.5%.
The core of the novel pharmaceutical formulation with controlled release of active substances also contains other dried pharmaceutically acceptable auxiliary substances. The novel pharmaceutical formulation with controlled release of active substances may contain one or more fillers such as lactose, saccharose, glucose, starch, microcrystalline cellulose, mannitol, sorbitol, calcium hydrogen phosphate, aluminum silicate, sodium chloride and others, one or more binders such as starch, gelatine, polyvinyl pyrrolidone, cross-linked polyvinyl pyrrolidone, sodium alginate, micro-crystalline cellulose, carboxymethyl cellulose, lower substituted hydroxypropyl cellulose and others, one or more disintegrators such as starch, sodium cross-linked carboxymethyl cellulose, cross-linked polyvinyl pyrrolidone, sodium starch glycolate and others, one or more glidants such as polyethylene glycols of different molecular weights, magnesium stearate, calcium stearate, aluminium stearate, stearic acid, palmitic acid, cetanol, stearol, talc and others, one or more lubricants such as stearic acid, magnesium stearate, calcium stearate, aluminum stearate, siliconized talc and others. Pharmaceutically acceptable auxiliary substances used are dried before use so that their weight loss at drying is less than 1.0%, preferably less than 0.5 % with regard to the total weight of a particular pharmaceutical auxiliary substance.
The cores are coated with a gastro-resistant coating which prevents the release of the active substance in the acidic gastric medium and at the same time makes possible a controlled release of the active substance from the novel pharmaceutical form in the small intestine. The gastro-resistant coating consists of cellulose derivatives such as cellulose acetophthalate, hydroxypropylmethyl cellulose phthalate, copolymers of metacrylic acid, shellac, ethyl cellulose, hydroxypropylmethyl cellulose acetate succinate. Besides said polymers the gastro-resistant coating may additionally contain one or more plasticizers such as polyethylene glycols of different molecular weights, triethyl citrate, dibutyl sebacate, tributyl citrate, cetyl alcohol, olive oil or castor oil, monoglycerides and other common pharmaceutically acceptable auxiliary substances which are used in the preparation of gastro-resistant coatings such as talc, Polysorbate 80, pigments and magnesium stearate. The amount of gastro-resistant coating applied is from 5 to 30 wt.% with regard to the total core weight. The used pharmaceutically acceptable auxiliary substances forming the gastro-resistant coating are dried before use so that their weight loss at drying is less than 1.0%, preferably less than 0.5% of the total weight of the individual pharmaceutical auxiliary substance.
Between the core and the gastro-resistant coating one or more intermediate coatings may be optionally applied in order to cover irregularities on the surface of the cores that are porous due to the anhydrous granulation of active substances and dried pharmaceutically acceptable auxiliary substances. The intermediate coating consists of cellulose ether polymers soluble in organic solvents, such as hydroxypropylmethyl cellulose, hydroxypropyl cellulose, methyl cellulose, sodium carboxymethyl cellulose, ethyl cellulose, polivinyl pyrrolidones, vinyl pyrrolidone/vinyl acetate copolymer, polymetacrylates. The amount of the applied optional intermediate coating is from 0 to 15 wt.% with regard to the total core weight. The used pharmaceutically acceptable auxiliary substances forming the intermediate coating are dried before use so that their weight loss at drying is less than 1.0%, preferably less than 0.5% of the total weight of the individual pharmaceutical auxiliary substance.
Another object of the invention is a process for the preparation of the novel pharmaceutical formulation with controlled release of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating.
The first step of the process for the preparation of the novel pharmaceutical formulation with controlled release of active substances is anhydrous granulation of an active substance and dried pharmaceutically acceptable auxiliary substances so that their weight loss at drying is less than 1.0%, preferably less than 0.5%. Organic solvents used in the process of anhydrous granulation should contain less than 0.2% of water. The process of anhydrous granulation is carried out in such a way that a dried surfactant is dissolved in an organic solvent at room temperature and the obtained solution is sprayed in a fluidized bed granulator onto a homogenous powdery mixture containing active substances, a dried binder soluble in organic solvents, a dried cellulose ether and other dried pharmaceutically acceptable auxiliary substances. The organic solvents used for that purpose are selected from the group of alcohols, ketones, esters, ethers, aliphatic hydrocarbons, halogenated hydrocarbons, cycloaliphatic, aromatic, heterocyclic solvents and mixtures thereof. The plastic mixture obtained in the process of anhydrous granulation is formed into granules or pellet cores by common pharmaceutical technological processes such as extruding and spheronizing methods. The pellet cores or granules so formed are dried in a fluidized bed or in a chamber dryer at the temperature of inlet air from 35 to 45xc2x0 C. until the weight loss at drying is less than 1.0 %, preferably less than 0.5% of the total weight of the pellet cores or granules. Under the addition of dried pharmaceutically acceptable auxiliary substances, dry pellet cores or granules may be compressed into tablets, which in further procedure are coated with a gastro-resistant coating. In view of the porosity of the tablets, also one or more intermediate coatings may be applied between the tablet and the gastro-resistant coating. Alternatively, pellet cores or granules prepared by means of anhydrous granulation may be coated with gastro-resistant coating and then filled into capsules or bags or compressed into tablets under addition of dried pharmaceutically acceptable auxiliary substances. In view of the porosity of pellet cores or granules, also one or more intermediate coatings may be applied between the pellet core or granule and the gastro-resistant coating.
The gastro-resistant coating and the optional intermediate coating are prepared in such a way that dried polymers with the weight loss at drying of less than 1.0%, preferably less than 0.5%, are dissolved in organic solvents containing less than 0.2% water. As organic solvents ethanol, methanol, isopropanol, acetone, methylene chloride, carbon tetrachloride or a mixture thereof may be used. To the polymer solution thus formed also the remaining dried pharmaceutically acceptable auxiliary substances with the weight loss at drying of less than 1.0%, preferably less than 0.5%, such as plasticizers, antiadhesives, fillers, wetting agents, pigments are added. The solution or suspension thus formed is sprayed onto cores in a fluidized bed granulator.
After the completed process of coating with gastro-resistant coating and optionally with an intermediate coating, the pellets of the novel pharmaceutical formulation with controlled release of an active substance according to the invention are dried in a fluidized bed at the temperature of inlet air from 30 to 35xc2x0 C. until the weight loss at drying is less than 1.0%, preferably less than 0.5% of the total weight of pellets of the novel pharmaceutical formulation.
By the method of stabilization of active substances on the principle of anhydrous granulation of active substances and dried pharmaceutically acceptable auxiliary substances in the preparation of the novel phamaceutical formulation according to the invention, the stability of active substances that are unstable in acidic medium, unstable when stored for longer periods of time in the presence of water and at the same time sensitive to heating, is essentially enhanced. The use of the process of anhydrous granulation makes possible the preparation of the novel pharmaceutical formulation according to the invention at lower temperatures and with shorter times of drying the granulate. In all steps of the process for the preparation of the novel pharmaceutical formulation according to the invention, all substances entering the process contain less than 1.0%, preferably less than 0.5% water. By the selection of solvents with a boiling point lower than the boiling point of water, the removal thereof under milder conditions and in a shorter time is made possible, which contributes to a better stability of active substances that are sensitive to heating. Because of the use of the process of anhydrous granulation, it is not necessary to apply an intermediate coating between the core with the active substance and the gastro-resistant coating in order to provide for the required stability of the active substance in the pharmaceutical formulation. Since a smaller number of auxiliary substances is present in the novel pharmaceutical formulation according to the invention, less strain is put on the organism.